public class ADBoard {
    Advertisement adver;
    public void setAdvertisement(Advertisement a){
        adver = a;

    }
    public void show(){
        if (adver == null) {
            System.out.println("这是一个空广告牌");
        }else {
            adver.showAdvertisement();
            System.out.println(adver.getCorpName());
        }
    }
}
